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Neurohormonal Profile Before and After β‐Blockade in Patients with Neurocardiogenic Syncope
Author(s) -
ROUL GERALD,
RIEHLALEIL VERONIQUE,
GERMAIN PHILIPPE,
BAREISS PIERRE
Publication year - 1999
Publication title -
pacing and clinical electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.686
H-Index - 101
eISSN - 1540-8159
pISSN - 0147-8389
DOI - 10.1111/j.1540-8159.1999.tb00566.x
Subject(s) - medicine , epinephrine , beta blocker , syncope (phonology) , vasovagal syncope , group b , vasopressin , anesthesia , norepinephrine , cardiology , heart failure , dopamine
Our objective was to evaluate the effects of β‐blockers on the neurohormonal profile, particularly vasopressin (VP) release, in vasovagal syncope and to gain further insight on the pathophysiology of this syndrome. Patients (≤75 years) with no cardiovascular, neurological disorders, or contraindications to the use of isoproterenol or β‐blockers and being explored for unexplained syncope were included. An 80± HUT was performed under identical conditions. After a 25‐min period of passive tilt, isoproterenol was infused at a rate of 1–5 μg/mn if required. Two groups matched for age and sex were considered: a HUT‐positive and a HUT‐negative group. The HUT‐positive group was then given β‐blockers, subsequently reassessed, and divided into two subgroups: a β‐blocker nonresponder group and a β‐blocker responder group. Blood samples for assays of norepinephrine (NE), epinephrine (E), and VP were taken at baseline and the end of the procedure. In all, 44 subjects entered the study, 22 in each group. The HUT‐positive group exhibited an obvious lesser increase in plasma NE and a clear‐cut rise in plasma E and VP compared to the HUT‐negative group (P < 0.05). Even though no patient in the HUT‐positive group reported recurrent symptoms under treatment, the second HUT could distinguish two subgroups: a β‐blocker nonresponder group (n = 12) whose HUT remained positive and a β‐blocker responder group (n = 10) whose HUT was normalized. The time course of plasma E and VP during the second HUT was similar to that for the HUT‐positive and HUT‐negative groups. In conclusion, the efficacy of β‐blockers is associated not only with a reduction of the sympathoadrenal stimulation seen in vasovagal syncope but also with a lower release of VP suggesting that low‐pressure baroreceptors might be involved in VP release.